System and method for i/o fencing based on storage array access control list

ABSTRACT

A method, computer program product, and computer system for creating, by a computing device, a logical unit number (LUN) on a storage array node of a storage system. An identifier of the LUN of the storage array node may be provided to a computing system, wherein the computing system includes one of a host, a server, and the storage array node. An access control list (ACL) of the computing system may be created. The ACL of the computing system may be applied to the LUN based upon, at least in part, the identifier. The LUN may be discovered and mapped at the computing system. It may be determined that the computing system has failed. The ACL of the computing system that has failed may be removed from the LUN to prevent the computing system that has failed from accessing the LUN.

BACKGROUND

Generally, nodes of a computer cluster may coordinate among themselvesto use shared resources. At some point of a time, a node of the clustermay start performing erratically, because of some failure or crash. Ifthis erratic node accesses the shared resource, then this may lead todata corruption.

BRIEF SUMMARY OF DISCLOSURE

In one example implementation, a method, performed by one or morecomputing devices, may include but is not limited to creating, by acomputing device, a logical unit number (LUN) on a storage array node ofa storage system. An identifier of the LUN of the storage array node maybe provided to a computing system, wherein the computing system includesone of a host, a server, and the storage array node. An access controllist (ACL) of the computing system may be created. The ACL of thecomputing system may be applied to the LUN based upon, at least in part,the identifier. The LUN may be discovered and mapped at the computingsystem. It may be determined that the computing system has failed. TheACL of the computing system that has failed may be removed from the LUNto prevent the computing system that has failed from accessing the LUN.

One or more of the following example features may be included. Theidentifier may include a World Wide Identifier (WWID) of the LUN. Theidentifier may include a iSCSI Qualified Name (IQN) of the LUN. It maybe determined from the computing system that the LUN with the identifierexists in the storage system. The ACL of the host may be fetched whenthe LUN with the identifier exists in the storage system. Applying tothe LUN the ACL may include sending a dictionary to the storage system.The identifier may include a World Wide Identifier (WWID) of the LUN anda iSCSI Qualified Name (IQN) of the LUN.

In another example implementation, a computing system may include one ormore processors and one or more memories configured to performoperations that may include but are not limited to creating a logicalunit number (LUN) on a storage array node of a storage system. Anidentifier of the LUN of the storage array node may be provided to acomputing system, wherein the computing system includes one of a host, aserver, and the storage array node. An access control list (ACL) of thecomputing system may be created. The ACL of the computing system may beapplied to the LUN based upon, at least in part, the identifier. The LUNmay be discovered and mapped at the computing system. It may bedetermined that the computing system has failed. The ACL of thecomputing system that has failed may be removed from the LUN to preventthe computing system that has failed from accessing the LUN.

One or more of the following example features may be included. Theidentifier may include a World Wide Identifier (WWID) of the LUN. Theidentifier may include a iSCSI Qualified Name (IQN) of the LUN. It maybe determined from the computing system that the LUN with the identifierexists in the storage system. The ACL of the host may be fetched whenthe LUN with the identifier exists in the storage system. Applying tothe LUN the ACL may include sending a dictionary to the storage system.The identifier may include a World Wide Identifier (WWID) of the LUN anda iSCSI Qualified Name (IQN) of the LUN.

In another example implementation, a computer program product may resideon a computer readable storage medium having a plurality of instructionsstored thereon which, when executed across one or more processors, maycause at least a portion of the one or more processors to performoperations that may include but are not limited to creating a logicalunit number (LUN) on a storage array node of a storage system. Anidentifier of the LUN of the storage array node may be provided to acomputing system, wherein the computing system includes one of a host, aserver, and the storage array node. An access control list (ACL) of thecomputing system may be created. The ACL of the computing system may beapplied to the LUN based upon, at least in part, the identifier. The LUNmay be discovered and mapped at the computing system. It may bedetermined that the computing system has failed. The ACL of thecomputing system that has failed may be removed from the LUN to preventthe computing system that has failed from accessing the LUN.

One or more of the following example features may be included. Theidentifier may include a World Wide Identifier (WWID) of the LUN. Theidentifier may include a iSCSI Qualified Name (IQN) of the LUN. It maybe determined from the computing system that the LUN with the identifierexists in the storage system. The ACL of the host may be fetched whenthe LUN with the identifier exists in the storage system. Applying tothe LUN the ACL may include sending a dictionary to the storage system.The identifier may include a World Wide Identifier (WWID) of the LUN anda iSCSI Qualified Name (IQN) of the LUN.

The details of one or more example implementations are set forth in theaccompanying drawings and the description below. Other possible examplefeatures and/or possible example advantages will become apparent fromthe description, the drawings, and the claims. Some implementations maynot have those possible example features and/or possible exampleadvantages, and such possible example features and/or possible exampleadvantages may not necessarily be required of some implementations.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an example diagrammatic view of a fencing process coupled toan example distributed computing network according to one or moreexample implementations of the disclosure;

FIG. 2 is an example diagrammatic view of a storage system of FIG. 1according to one or more example implementations of the disclosure;

FIG. 3 is an example diagrammatic view of a storage target of FIG. 1according to one or more example implementations of the disclosure;

FIG. 4 is an example flowchart of a fencing process according to one ormore example implementations of the disclosure; and

FIG. 5 is an example diagrammatic view of a cluster according to one ormore example implementations of the disclosure.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION System Overview:

In some implementations, the present disclosure may be embodied as amethod, system, or computer program product. Accordingly, in someimplementations, the present disclosure may take the form of an entirelyhardware implementation, an entirely software implementation (includingfirmware, resident software, micro-code, etc.) or an implementationcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore, insome implementations, the present disclosure may take the form of acomputer program product on a computer-usable storage medium havingcomputer-usable program code embodied in the medium.

In some implementations, any suitable computer usable or computerreadable medium (or media) may be utilized. The computer readable mediummay be a computer readable signal medium or a computer readable storagemedium. The computer-usable, or computer-readable, storage medium(including a storage device associated with a computing device or clientelectronic device) may be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, device, or any suitable combination ofthe foregoing. More specific examples (a non-exhaustive list) of thecomputer-readable medium may include the following: an electricalconnection having one or more wires, a portable computer diskette, ahard disk, a random access memory (RAM), a read-only memory (ROM), anerasable programmable read-only memory (EPROM or Flash memory), anoptical fiber, a portable compact disc read-only memory (CD-ROM), anoptical storage device, a digital versatile disk (DVD), a static randomaccess memory (SRAM), a memory stick, a floppy disk, a mechanicallyencoded device such as punch-cards or raised structures in a groovehaving instructions recorded thereon, a media such as those supportingthe internet or an intranet, or a magnetic storage device. Note that thecomputer-usable or computer-readable medium could even be a suitablemedium upon which the program is stored, scanned, compiled, interpreted,or otherwise processed in a suitable manner, if necessary, and thenstored in a computer memory. In the context of the present disclosure, acomputer-usable or computer-readable, storage medium may be any tangiblemedium that can contain or store a program for use by or in connectionwith the instruction execution system, apparatus, or device.

In some implementations, a computer readable signal medium may include apropagated data signal with computer readable program code embodiedtherein, for example, in baseband or as part of a carrier wave. In someimplementations, such a propagated signal may take any of a variety offorms, including, but not limited to, electro-magnetic, optical, or anysuitable combination thereof. In some implementations, the computerreadable program code may be transmitted using any appropriate medium,including but not limited to the internet, wireline, optical fibercable, RF, etc. In some implementations, a computer readable signalmedium may be any computer readable medium that is not a computerreadable storage medium and that can communicate, propagate, ortransport a program for use by or in connection with an instructionexecution system, apparatus, or device.

In some implementations, computer program code for carrying outoperations of the present disclosure may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Java®, Smalltalk, C++ or the like.Java® and all Java-based trademarks and logos are trademarks orregistered trademarks of Oracle and/or its affiliates. However, thecomputer program code for carrying out operations of the presentdisclosure may also be written in conventional procedural programminglanguages, such as the “C” programming language, PASCAL, or similarprogramming languages, as well as in scripting languages such asJavascript, PERL, or Python. The program code may execute entirely onthe user's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough a local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theinternet using an Internet Service Provider). In some implementations,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGAs) or other hardwareaccelerators, micro-controller units (MCUs), or programmable logicarrays (PLAs) may execute the computer readable programinstructions/code by utilizing state information of the computerreadable program instructions to personalize the electronic circuitry,in order to perform aspects of the present disclosure.

In some implementations, the flowchart and block diagrams in the figuresillustrate the architecture, functionality, and operation of possibleimplementations of apparatus (systems), methods and computer programproducts according to various implementations of the present disclosure.Each block in the flowchart and/or block diagrams, and combinations ofblocks in the flowchart and/or block diagrams, may represent a module,segment, or portion of code, which comprises one or more executablecomputer program instructions for implementing the specified logicalfunction(s)/act(s). These computer program instructions may be providedto a processor of a general purpose computer, special purpose computer,or other programmable data processing apparatus to produce a machine,such that the computer program instructions, which may execute via theprocessor of the computer or other programmable data processingapparatus, create the ability to implement one or more of thefunctions/acts specified in the flowchart and/or block diagram block orblocks or combinations thereof. It should be noted that, in someimplementations, the functions noted in the block(s) may occur out ofthe order noted in the figures (or combined or omitted). For example,two blocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved.

In some implementations, these computer program instructions may also bestored in a computer-readable memory that can direct a computer or otherprogrammable data processing apparatus to function in a particularmanner, such that the instructions stored in the computer-readablememory produce an article of manufacture including instruction meanswhich implement the function/act specified in the flowchart and/or blockdiagram block or blocks or combinations thereof.

In some implementations, the computer program instructions may also beloaded onto a computer or other programmable data processing apparatusto cause a series of operational steps to be performed (not necessarilyin a particular order) on the computer or other programmable apparatusto produce a computer implemented process such that the instructionswhich execute on the computer or other programmable apparatus providesteps for implementing the functions/acts (not necessarily in aparticular order) specified in the flowchart and/or block diagram blockor blocks or combinations thereof.

Referring now to the example implementation of FIG. 1, there is shownfencing process 10 that may reside on and may be executed by a computer(e.g., computer 12), which may be connected to a network (e.g., network14) (e.g., the internet or a local area network). Examples of computer12 (and/or one or more of the client electronic devices noted below) mayinclude, but are not limited to, a storage system (e.g., a NetworkAttached Storage (NAS) system, a Storage Area Network (SAN)), a personalcomputer(s), a laptop computer(s), mobile computing device(s), a servercomputer, a series of server computers, a mainframe computer(s), or acomputing cloud(s). As is known in the art, a SAN may include one ormore of the client electronic devices, including a RAID device and a NASsystem. In some implementations, each of the aforementioned may begenerally described as a computing device. In certain implementations, acomputing device may be a physical or virtual device. In manyimplementations, a computing device may be any device capable ofperforming operations, such as a dedicated processor, a portion of aprocessor, a virtual processor, a portion of a virtual processor,portion of a virtual device, or a virtual device. In someimplementations, a processor may be a physical processor or a virtualprocessor. In some implementations, a virtual processor may correspondto one or more parts of one or more physical processors. In someimplementations, the instructions/logic may be distributed and executedacross one or more processors, virtual or physical, to execute theinstructions/logic. Computer 12 may execute an operating system, forexample, but not limited to, Microsoft® Windows®; Mac® OS X®; Red Hat®Linux®, Windows® Mobile, Chrome OS, Blackberry OS, Fire OS, or a customoperating system. (Microsoft and Windows are registered trademarks ofMicrosoft Corporation in the United States, other countries or both; Macand OS X are registered trademarks of Apple Inc. in the United States,other countries or both; Red Hat is a registered trademark of Red HatCorporation in the United States, other countries or both; and Linux isa registered trademark of Linus Torvalds in the United States, othercountries or both).

In some implementations, as will be discussed below in greater detail, afencing process, such as fencing process 10 of FIG. 1, may create, by acomputing device, a logical unit number (LUN) on a storage array node ofa storage system. An identifier of the LUN of the storage array node maybe provided to a computing system, wherein the computing system includesone of a host, a server, and the storage array node. An access controllist (ACL) of the computing system may be created. The ACL of thecomputing system may be applied to the LUN based upon, at least in part,the identifier. The LUN may be discovered and mapped at the computingsystem. It may be determined that the computing system has failed. TheACL of the computing system that has failed may be removed from the LUNto prevent the computing system that has failed from accessing the LUN.

In some implementations, the instruction sets and subroutines of fencingprocess 10, which may be stored on storage device, such as storagedevice 16, coupled to computer 12, may be executed by one or moreprocessors and one or more memory architectures included within computer12. In some implementations, storage device 16 may include but is notlimited to: a hard disk drive; all forms of flash memory storagedevices; a tape drive; an optical drive; a RAID array (or other array);a random access memory (RAM); a read-only memory (ROM); or combinationthereof. In some implementations, storage device 16 may be organized asan extent, an extent pool, a RAID extent (e.g., an example 4D+1P R5,where the RAID extent may include, e.g., five storage device extentsthat may be allocated from, e.g., five different storage devices), amapped RAID (e.g., a collection of RAID extents), or combinationthereof.

In some implementations, network 14 may be connected to one or moresecondary networks (e.g., network 18), examples of which may include butare not limited to: a local area network; a wide area network or othertelecommunications network facility; or an intranet, for example. Thephrase “telecommunications network facility,” as used herein, may referto a facility configured to transmit, and/or receive transmissionsto/from one or more mobile client electronic devices (e.g., cellphones,etc.) as well as many others.

In some implementations, computer 12 may include a data store, such as adatabase (e.g., relational database, object-oriented database,triplestore database, etc.) and may be located within any suitablememory location, such as storage device 16 coupled to computer 12. Insome implementations, data, metadata, information, etc. describedthroughout the present disclosure may be stored in the data store. Insome implementations, computer 12 may utilize any known databasemanagement system such as, but not limited to, DB2, in order to providemulti-user access to one or more databases, such as the above notedrelational database. In some implementations, the data store may also bea custom database, such as, for example, a flat file database or an XMLdatabase. In some implementations, any other form(s) of a data storagestructure and/or organization may also be used. In some implementations,fencing process 10 may be a component of the data store, a standaloneapplication that interfaces with the above noted data store and/or anapplet/application that is accessed via client applications 22, 24, 26,28. In some implementations, the above noted data store may be, in wholeor in part, distributed in a cloud computing topology. In this way,computer 12 and storage device 16 may refer to multiple devices, whichmay also be distributed throughout the network.

In some implementations, computer 12 may execute a storage managementapplication (e.g., storage management application 21), examples of whichmay include, but are not limited to, e.g., a storage system application,a cloud computing application, a data synchronization application, adata migration application, a garbage collection application, or otherapplication that allows for the implementation and/or management of datain a clustered (or non-clustered) environment (or the like). In someimplementations, fencing process 10 and/or storage managementapplication 21 may be accessed via one or more of client applications22, 24, 26, 28. In some implementations, fencing process 10 may be astandalone application, or may be an applet/application/script/extensionthat may interact with and/or be executed within storage managementapplication 21, a component of storage management application 21, and/orone or more of client applications 22, 24, 26, 28. In someimplementations, storage management application 21 may be a standaloneapplication, or may be an applet/application/script/extension that mayinteract with and/or be executed within fencing process 10, a componentof fencing process 10, and/or one or more of client applications 22, 24,26, 28. In some implementations, one or more of client applications 22,24, 26, 28 may be a standalone application, or may be anapplet/application/script/extension that may interact with and/or beexecuted within and/or be a component of fencing process 10 and/orstorage management application 21. Examples of client applications 22,24, 26, 28 may include, but are not limited to, e.g., a storage systemapplication, a cloud computing application, a data synchronizationapplication, a data migration application, a garbage collectionapplication, or other application that allows for the implementationand/or management of data in a clustered (or non-clustered) environment(or the like), a standard and/or mobile web browser, an emailapplication (e.g., an email client application), a textual and/or agraphical user interface, a customized web browser, a plugin, anApplication Programming Interface (API), or a custom application. Theinstruction sets and subroutines of client applications 22, 24, 26, 28,which may be stored on storage devices 30, 32, 34, 36, coupled to clientelectronic devices 38, 40, 42, 44, may be executed by one or moreprocessors and one or more memory architectures incorporated into clientelectronic devices 38, 40, 42, 44.

In some implementations, one or more of storage devices 30, 32, 34, 36,may include but are not limited to: hard disk drives; flash drives, tapedrives; optical drives; RAID arrays; random access memories (RAM); andread-only memories (ROM).

Examples of client electronic devices 38, 40, 42, 44 (and/or computer12) may include, but are not limited to, a personal computer (e.g.,client electronic device 38), a laptop computer (e.g., client electronicdevice 40), a smart/data-enabled, cellular phone (e.g., clientelectronic device 42), a notebook computer (e.g., client electronicdevice 44), a tablet, a server, a television, a smart television, asmart speaker, an Internet of Things (IoT) device, a media (e.g., video,photo, etc.) capturing device, and a dedicated network device. Clientelectronic devices 38, 40, 42, 44 may each execute an operating system,examples of which may include but are not limited to, Android™, Apple®iOS®, Mac® OS X®; Red Hat® Linux®, Windows® Mobile, Chrome OS,Blackberry OS, Fire OS, or a custom operating system.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality offencing process 10 (and vice versa). Accordingly, in someimplementations, fencing process 10 may be a purely server-sideapplication, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or fencing process10.

In some implementations, one or more of client applications 22, 24, 26,28 may be configured to effectuate some or all of the functionality ofstorage management application 21 (and vice versa). Accordingly, in someimplementations, storage management application 21 may be a purelyserver-side application, a purely client-side application, or a hybridserver-side/client-side application that is cooperatively executed byone or more of client applications 22, 24, 26, 28 and/or storagemanagement application 21. As one or more of client applications 22, 24,26, 28, fencing process 10, and storage management application 21, takensingly or in any combination, may effectuate some or all of the samefunctionality, any description of effectuating such functionality viaone or more of client applications 22, 24, 26, 28, fencing process 10,storage management application 21, or combination thereof, and anydescribed interaction(s) between one or more of client applications 22,24, 26, 28, fencing process 10, storage management application 21, orcombination thereof to effectuate such functionality, should be taken asan example only and not to limit the scope of the disclosure.

In some implementations, one or more of users 46, 48, 50, 52 may accesscomputer 12 and fencing process 10 (e.g., using one or more of clientelectronic devices 38, 40, 42, 44) directly through network 14 orthrough secondary network 18. Further, computer 12 may be connected tonetwork 14 through secondary network 18, as illustrated with phantomlink line 54. Fencing process 10 may include one or more userinterfaces, such as browsers and textual or graphical user interfaces,through which users 46, 48, 50, 52 may access fencing process 10.

In some implementations, the various client electronic devices may bedirectly or indirectly coupled to network 14 (or network 18). Forexample, client electronic device 38 is shown directly coupled tonetwork 14 via a hardwired network connection. Further, clientelectronic device 44 is shown directly coupled to network 18 via ahardwired network connection. Client electronic device 40 is shownwirelessly coupled to network 14 via wireless communication channel 56established between client electronic device 40 and wireless accesspoint (i.e., WAP) 58, which is shown directly coupled to network 14. WAP58 may be, for example, an IEEE 802.11a, 802.11b, 802.11g, 802.11n,802.11ac, Wi-Fi®, RFID, and/or Bluetooth™ (including Bluetooth™ LowEnergy) device that is capable of establishing wireless communicationchannel 56 between client electronic device 40 and WAP 58. Clientelectronic device 42 is shown wirelessly coupled to network 14 viawireless communication channel 60 established between client electronicdevice 42 and cellular network/bridge 62, which is shown by exampledirectly coupled to network 14.

In some implementations, some or all of the IEEE 802.11x specificationsmay use Ethernet protocol and carrier sense multiple access withcollision avoidance (i.e., CSMA/CA) for path sharing. The various802.11x specifications may use phase-shift keying (i.e., PSK) modulationor complementary code keying (i.e., CCK) modulation, for example.Bluetooth™ (including Bluetooth™ Low Energy) is a telecommunicationsindustry specification that allows, e.g., mobile phones, computers,smart phones, and other electronic devices to be interconnected using ashort-range wireless connection. Other forms of interconnection (e.g.,Near Field Communication (NFC)) may also be used.

In some implementations, various I/O requests (e.g., I/O request 15) maybe sent from, e.g., client applications 22, 24, 26, 28 to, e.g.,computer 12. Examples of I/O request 15 may include but are not limitedto, data write requests (e.g., a request that content be written tocomputer 12) and data read requests (e.g., a request that content beread from computer 12).

Data Storage System:

Referring also to the example implementation of FIGS. 2-3 (e.g., wherecomputer 12 may be configured as a data storage system), computer 12 mayinclude storage processor 100 and a plurality of storage targets (e.g.,storage targets 102, 104, 106, 108, 110). In some implementations,storage targets 102, 104, 106, 108, 110 may include any of theabove-noted storage devices. In some implementations, storage targets102, 104, 106, 108, 110 may be configured to provide various levels ofperformance and/or high availability. For example, storage targets 102,104, 106, 108, 110 may be configured to form a non-fully-duplicativefault-tolerant data storage system (such as a non-fully-duplicative RAIDdata storage system), examples of which may include but are not limitedto: RAID 3 arrays, RAID 4 arrays, RAID 5 arrays, and/or RAID 6 arrays.It will be appreciated that various other types of RAID arrays may beused without departing from the scope of the present disclosure.

While in this particular example, computer 12 is shown to include fivestorage targets (e.g., storage targets 102, 104, 106, 108, 110), this isfor example purposes only and is not intended limit the presentdisclosure. For instance, the actual number of storage targets may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

Further, the storage targets (e.g., storage targets 102, 104, 106, 108,110) included with computer 12 may be configured to form a plurality ofdiscrete storage arrays. For instance, and assuming for example purposesonly that computer 12 includes, e.g., ten discrete storage targets, afirst five targets (of the ten storage targets) may be configured toform a first RAID array and a second five targets (of the ten storagetargets) may be configured to form a second RAID array.

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may be configured to store coded data (e.g., via storagemanagement process 21), wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage targets102, 104, 106, 108, 110. Examples of such coded data may include but isnot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage targets 102, 104, 106, 108, 110 or maybe stored within a specific storage target.

Examples of storage targets 102, 104, 106, 108, 110 may include one ormore data arrays, wherein a combination of storage targets 102, 104,106, 108, 110 (and any processing/control systems associated withstorage management application 21) may form data array 112.

The manner in which computer 12 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, computer 12 may be configured as a SAN (i.e., a Storage AreaNetwork), in which storage processor 100 may be, e.g., a dedicatedcomputing system and each of storage targets 102, 104, 106, 108, 110 maybe a RAID device. An example of storage processor 100 may include but isnot limited to a VPLEX system offered by Dell EMC of Hopkinton, Mass.

In the example where computer 12 is configured as a SAN, the variouscomponents of computer 12 (e.g., storage processor 100, and storagetargets 102, 104, 106, 108, 110) may be coupled using networkinfrastructure 114, examples of which may include but are not limited toan Ethernet (e.g., Layer 2 or Layer 3) network, a fiber channel network,an InfiniBand network, or any other circuit switched/packet switchednetwork.

As discussed above, various I/O requests (e.g., I/O request 15) may begenerated. For example, these I/O requests may be sent from, e.g.,client applications 22, 24, 26, 28 to, e.g., computer 12.Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), these I/O requestsmay be internally generated within storage processor 100 (e.g., viastorage management process 21). Examples of I/O request 15 may includebut are not limited to data write request 116 (e.g., a request thatcontent 118 be written to computer 12) and data read request 120 (e.g.,a request that content 118 be read from computer 12).

In some implementations, during operation of storage processor 100,content 118 to be written to computer 12 may be received and/orprocessed by storage processor 100 (e.g., via storage management process21). Additionally/alternatively (e.g., when storage processor 100 isconfigured as an application server or otherwise), content 118 to bewritten to computer 12 may be internally generated by storage processor100 (e.g., via storage management process 21).

As discussed above, the instruction sets and subroutines of storagemanagement application 21, which may be stored on storage device 16included within computer 12, may be executed by one or more processorsand one or more memory architectures included with computer 12.Accordingly, in addition to being executed on storage processor 100,some or all of the instruction sets and subroutines of storagemanagement application 21 (and/or fencing process 10) may be executed byone or more processors and one or more memory architectures includedwith data array 112.

In some implementations, storage processor 100 may include front endcache memory system 122. Examples of front end cache memory system 122may include but are not limited to a volatile, solid-state, cache memorysystem (e.g., a dynamic RAM cache memory system), a non-volatile,solid-state, cache memory system (e.g., a flash-based, cache memorysystem), and/or any of the above-noted storage devices.

In some implementations, storage processor 100 may initially storecontent 118 within front end cache memory system 122. Depending upon themanner in which front end cache memory system 122 is configured, storageprocessor 100 (e.g., via storage management process 21) may immediatelywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-through cache) or may subsequentlywrite content 118 to data array 112 (e.g., if front end cache memorysystem 122 is configured as a write-back cache).

In some implementations, one or more of storage targets 102, 104, 106,108, 110 may include a backend cache memory system. Examples of thebackend cache memory system may include but are not limited to avolatile, solid-state, cache memory system (e.g., a dynamic RAM cachememory system), a non-volatile, solid-state, cache memory system (e.g.,a flash-based, cache memory system), and/or any of the above-notedstorage devices.

Storage Targets:

As discussed above, one or more of storage targets 102, 104, 106, 108,110 may be a RAID device. For instance, and referring also to FIG. 3,there is shown example target 150, wherein target 150 may be one exampleimplementation of a RAID implementation of, e.g., storage target 102,storage target 104, storage target 106, storage target 108, and/orstorage target 110. An example of target 150 may include but is notlimited to a VNX system offered by Dell EMC of Hopkinton, Mass. Examplesof storage devices 154, 156, 158, 160, 162 may include one or moreelectro-mechanical hard disk drives, one or more solid-state/flashdevices, and/or any of the above-noted storage devices. It will beappreciated that while the term “disk” or “drive” may be usedthroughout, these may refer to and be used interchangeably with anytypes of appropriate storage devices as the context and functionality ofthe storage device permits.

In some implementations, target 150 may include storage processor 152and a plurality of storage devices (e.g., storage devices 154, 156, 158,160, 162). Storage devices 154, 156, 158, 160, 162 may be configured toprovide various levels of performance and/or high availability (e.g.,via storage management process 21). For example, one or more of storagedevices 154, 156, 158, 160, 162 (or any of the above-noted storagedevices) may be configured as a RAID 0 array, in which data is stripedacross storage devices. By striping data across a plurality of storagedevices, improved performance may be realized. However, RAID 0 arraysmay not provide a level of high availability. Accordingly, one or moreof storage devices 154, 156, 158, 160, 162 (or any of the above-notedstorage devices) may be configured as a RAID 1 array, in which data ismirrored between storage devices. By mirroring data between storagedevices, a level of high availability may be achieved as multiple copiesof the data may be stored within storage devices 154, 156, 158, 160,162.

While storage devices 154, 156, 158, 160, 162 are discussed above asbeing configured in a RAID 0 or RAID 1 array, this is for examplepurposes only and not intended to limit the present disclosure, as otherconfigurations are possible. For example, storage devices 154, 156, 158,160, 162 may be configured as a RAID 3, RAID 4, RAID 5 or RAID 6 array.

While in this particular example, target 150 is shown to include fivestorage devices (e.g., storage devices 154, 156, 158, 160, 162), this isfor example purposes only and not intended to limit the presentdisclosure. For instance, the actual number of storage devices may beincreased or decreased depending upon, e.g., the level ofredundancy/performance/capacity required.

In some implementations, one or more of storage devices 154, 156, 158,160, 162 may be configured to store (e.g., via storage managementprocess 21) coded data, wherein such coded data may allow for theregeneration of data lost/corrupted on one or more of storage devices154, 156, 158, 160, 162. Examples of such coded data may include but arenot limited to parity data and Reed-Solomon data. Such coded data may bedistributed across all of storage devices 154, 156, 158, 160, 162 or maybe stored within a specific storage device.

The manner in which target 150 is implemented may vary depending upone.g., the level of redundancy/performance/capacity required. Forexample, target 150 may be a RAID device in which storage processor 152is a RAID controller card and storage devices 154, 156, 158, 160, 162are individual “hot-swappable” hard disk drives. Another example oftarget 150 may be a RAID system, examples of which may include but arenot limited to an NAS (i.e., Network Attached Storage) device or a SAN(i.e., Storage Area Network).

In some implementations, storage target 150 may execute all or a portionof storage management application 21. The instruction sets andsubroutines of storage management application 21, which may be stored ona storage device (e.g., storage device 164) coupled to storage processor152, may be executed by one or more processors and one or more memoryarchitectures included with storage processor 152. Storage device 164may include but is not limited to any of the above-noted storagedevices.

As discussed above, computer 12 may be configured as a SAN, whereinstorage processor 100 may be a dedicated computing system and each ofstorage targets 102, 104, 106, 108, 110 may be a RAID device.Accordingly, when storage processor 100 processes data requests 116,120, storage processor 100 (e.g., via storage management process 21) mayprovide the appropriate requests/content (e.g., write request 166,content 168 and read request 170) to, e.g., storage target 150 (which isrepresentative of storage targets 102, 104, 106, 108 and/or 110).

In some implementations, during operation of storage processor 152,content 168 to be written to target 150 may be processed by storageprocessor 152 (e.g., via storage management process 21). Storageprocessor 152 may include cache memory system 172. Examples of cachememory system 172 may include but are not limited to a volatile,solid-state, cache memory system (e.g., a dynamic RAM cache memorysystem) and/or a non-volatile, solid-state, cache memory system (e.g., aflash-based, cache memory system). During operation of storage processor152, content 168 to be written to target 150 may be received by storageprocessor 152 (e.g., via storage management process 21) and initiallystored (e.g., via storage management process 21) within front end cachememory system 172.

Generally, nodes of a computer cluster may coordinate among themselvesto use shared resources. At some point of a time, a node of the clustermay start performing erratically, because of some failure or crash. Ifthis erratic node accesses the shared resource, then this may lead todata corruption. The erratic node should be isolated/fenced from thecomputer cluster. There may be various ways used by cluster software tofence an erratic node (e.g., SCSI3 PR, Server console, network switchprogramming) and ensures that the erratic node is not able to access theshared data.

Some I/O fencing solutions may be either SCSI protocol dependent, serverpower dependent, FC switch based (e.g., disabling the FC port), and eachof these solutions have their limitations. For example, some may requireadditional hardware. Storage fencing using SCSI 3 PR may require keysper host and may incur additional checks in the I/O path at the storagearray. Generally, SCSI3 PR is not mandated in the SCSI specification andthe LUN is not supporting SCSI (NVMe). Storage fencing using FCswitch-based disabling may require switch data to be programmed for thefencing provisioning, adding complication and added user requirements.Power fencing may require additional power controllers to fence thefailing node, and dual power supply nodes need to be given specialtreatment. As such, as will be discussed below, the present disclosuremay provide I/O fencing in clusters based on an access control list of ahost present in a storage array volume.

The Fencing Process:

As discussed above and referring also at least to the exampleimplementations of FIGS. 4-5, fencing process 10 may create 400, by acomputing device, a logical unit number (LUN) on a storage array node ofa storage system. Fencing process 10 may provide 402 an identifier ofthe LUN of the storage array node to a computing system, wherein thecomputing system includes one of a host, a server, and the storage arraynode. Fencing process 10 may create 403 an access control list (ACL) ofthe computing system. Fencing process 10 may apply 404 the ACL of thecomputing system to the LUN based upon, at least in part, theidentifier. Fencing process 10 may discover and map 405 the LUN at thecomputing system. Fencing process 10 may determine 406 that thecomputing system has failed. Fencing process 10 may remove 408 the ACLof the computing system that has failed from the LUN to prevent thecomputing system that has failed from accessing the computing systemthat has failed.

As will be discussed below, fencing process 10 may enable an improvedand new technique for executing I/O fencing by using an access controllist (ACL) programmed for a logical unit number (LUN)/volume in astorage array. In some implementations, fencing process 10 may use aparticular framework (e.g., the REST framework) exposed by the storagearray to fetch, program and remove the host access to a LUN/volume. Insome implementations, array fencing software (e.g., fencing process 10)may be installed at the nodes of a cluster (hosts). At the time ofconfiguration of the cluster, the access of the host may be applied fora shared LUN. At the time of node failure, fencing process 10 may seethe failed node and remove its access control from the array, which mayprevent any further access to the (shared) LUN by the host.

For example, in some implementations, and referring at least to theexample implementation of FIG. 5, an example cluster 500 is shown. Inthe example, configuration of cluster 500 may include fencing process 10providing ACL based I/O fencing, which may be installed in the hosts ofthe cluster. The storage array IP, which may serve for the example RESTcommunication may be provided to fencing process 10.

In some implementations, fencing process 10 may create 400, by acomputing device, a logical unit number (LUN) on a storage array node ofa storage system, and may provide 402 an identifier of the LUN of thestorage array node to a computing system, wherein the computing systemincludes one of a host, a server, and the storage array node (e.g.,include a World Wide Identifier (WWID) and a iSCSI Qualified Name (IQN)of the LUN). For example, a user may (e.g., via fencing process 10and/or storage management process 21) create 400 a LUN/volume at thestorage array and may fetch the WWID of the LUN/volume. The user may(e.g., via fencing process 10 and/or storage management process 21)provide 402 the WWID of the LUN to fencing process 10 to create a device(e.g., a STONITH device).

In some implementations, fencing process 10 may determine 410 from thecomputing system that the LUN with the identifier exists in the storagesystem. For example, fencing process 10 may send one or more calls(e.g., REST calls) to the storage array and determine 410 whether or nota LUN with provided WWID exists on the storage array. In someimplementations, fencing process 10 may create 403 an access controllist (ACL) of the computing system and may fetch 412 the ACL of the hostwhen the LUN with the identifier exists in the storage system. Forexample, when the LUN with the identifier exists in the storage system,fencing process 10 may use its logic to fetch the ACL (e.g., IP, IQN orWWID) of the current host and may prepare a dictionary of this combinedinformation. Fencing process 10 may obtain the current IP of the hostusing, e.g., host commands, such as, use command “hostname -i” and mayobtain the initiator names, such as for iSCSI on Linux, fetch it from,e.g., /etc/iscsi/intiatorname.iscsi

In some implementations, the above-noted dictionary information that hasthe ACL information may look like the following non-limiting example:

{

“OperatingSystem”: “Other Single Path”,

“Name”: “10.44.234.112”,

“WWN or iSCSI Name”: “iqn.1994-05.com.redhat:XXXX-rhe174-node2”

“HBA Port type”: “iSCSI”

}

In some implementations, fencing process 10 may apply 404 the ACL of thecomputing system to the LUN based upon, at least in part, theidentifier, may discover and map 405 the LUN at the computing system,and in some implementations, applying 404 to the LUN the ACL may includesending 414 a dictionary to the storage system. For example, fencingprocess 10 may apply 404 the ACL of the current host to the LUN usingthe example and non-limiting REST framework. This may involves sending414 the above-noted dictionary via REST to the storage system (storagearray).

In some implementations, fencing process 10 may map and discover the LUNat the host side, and since the ACL is applied 404 as noted above, themap and discovery will pass successfully. As such, at the time ofconfiguration, all the participating hosts of the cluster have theiraccess control applied to the LUN, and the hosts may then start usingthe LUN for performing I/O operations.

In some implementations, fencing process 10 may determine 406 that thecomputing system has failed. For example, the computing system (e.g.,node) may be periodically pinged, and if there is no response for thenode, fencing process 10 may determine 406 that the node has failed. Itwill be appreciated that other techniques for detecting node failure mayalso be used without departing from the present disclosure. As such, theuse of pinging a node to detect node failure should be taken as exampleonly and not to otherwise limit the scope of the present disclosure.

In some implementations, fencing process 10 may remove 408 the ACL ofthe computing system that has failed from the LUN to prevent thecomputing system that has failed from accessing the LUN. For example,once a failed node is detected, the ACL of the failing node may beremoved 408 from the shared LUN, and may use the example REST call toremove the access control from the array.

As such, fencing process 10 may enable I/O fencing in clusters based onaccess control lists of a host present in a storage array volume, whichmay use, as an example only, REST/CLI framework from the storage array.At the time of the cluster formation, the host HBA wwid/IP address andiSCSI initiator IQN may be programmed in the array by fencing process10, and in case of a node failure, its host HBA wwid/IP address/iSCSIinitiator IQN accesses may be removed from the shared volume in thearray. Notably, fencing process 10 need not depend on SCSI as theunderlying transport, and does not require additional hardware forfencing. This may also enable the present disclosure to be implementedacross storage arrays (including different third party array platforms,as it may be array agnostic, SAN protocol agnostic (e.g., may work withFC, iSCSI, NVMe-oF, etc.), operating system agnostic (e.g., may beimplemented in VMware, Windows, Linux, etc.), and may work with virtualmachines (VMs) and physical servers.

The terminology used herein is for the purpose of describing particularimplementations only and is not intended to be limiting of thedisclosure. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. As used herein, the language “at least one of A, B,and C” (and the like) should be interpreted as covering only A, only B,only C, or any combination of the three, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps (notnecessarily in a particular order), operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps (not necessarily in a particular order),operations, elements, components, and/or groups thereof.

The corresponding structures, materials, acts, and equivalents (e.g., ofall means or step plus function elements) that may be in the claimsbelow are intended to include any structure, material, or act forperforming the function in combination with other claimed elements asspecifically claimed. The description of the present disclosure has beenpresented for purposes of illustration and description, but is notintended to be exhaustive or limited to the disclosure in the formdisclosed. Many modifications, variations, substitutions, and anycombinations thereof will be apparent to those of ordinary skill in theart without departing from the scope and spirit of the disclosure. Theimplementation(s) were chosen and described in order to explain theprinciples of the disclosure and the practical application, and toenable others of ordinary skill in the art to understand the disclosurefor various implementation(s) with various modifications and/or anycombinations of implementation(s) as are suited to the particular usecontemplated.

Having thus described the disclosure of the present application indetail and by reference to implementation(s) thereof, it will beapparent that modifications, variations, and any combinations ofimplementation(s) (including any modifications, variations,substitutions, and combinations thereof) are possible without departingfrom the scope of the disclosure defined in the appended claims.

What is claimed is:
 1. A computer-implemented method comprising:creating, by a computing device, a logical unit number (LUN) on astorage array node of a storage system; providing an identifier of theLUN of the storage array node to a computing system, wherein thecomputing system includes one of a host, a server, and the storage arraynode; creating an access control list (ACL) of the computing system;applying to the LUN the ACL of the computing system to the LUN basedupon, at least in part, the identifier; discovering and mapping the LUNat the computing system; determining that the computing system hasfailed; and removing the ACL of the computing system that has failedfrom the LUN to prevent the computing system that has failed fromaccessing the LUN.
 2. The computer-implemented method of claim 1 whereinthe identifier includes a World Wide Identifier (WWID) of the LUN. 3.The computer-implemented method of claim 1 wherein the identifierincludes a iSCSI Qualified Name (IQN) of the LUN.
 4. Thecomputer-implemented method of claim 1 further comprising determiningfrom the computing system that the LUN with the identifier exists in thestorage system.
 5. The computer-implemented method of claim 4 furthercomprising fetching the ACL of the host when the LUN with the identifierexists in the storage system.
 6. The computer-implemented method ofclaim 1 wherein applying to the LUN the ACL includes sending adictionary to the storage system.
 7. The computer-implemented method ofclaim 1 wherein the identifier includes a World Wide Identifier (WWID)of the LUN and a iSCSI Qualified Name (IQN) of the LUN.
 8. A computerprogram product residing on a computer readable storage medium having aplurality of instructions stored thereon which, when executed across oneor more processors, causes at least a portion of the one or moreprocessors to perform operations comprising: creating a logical unitnumber (LUN) on a storage array node of a storage system; providing anidentifier of the LUN of the storage array node to a computing system,wherein the computing system includes one of a host, a server, and thestorage array node; creating an access control list (ACL) of thecomputing system; applying to the LUN the ACL of the computing system tothe LUN based upon, at least in part, the identifier; discovering andmapping the LUN at the computing system; determining that the computingsystem has failed; and removing the ACL of the computing system that hasfailed from the LUN to prevent the computing system that has failed fromaccessing the LUN.
 9. The computer program product of claim 8 whereinthe identifier includes a World Wide Identifier (WWID) of the LUN. 10.The computer program product of claim 8 wherein the identifier includesa iSCSI Qualified Name (IQN) of the LUN.
 11. The computer programproduct of claim 8 wherein the operations further comprise determiningfrom the computing system that the LUN with the identifier exists in thestorage system.
 12. The computer program product of claim 11 wherein theoperations further comprise fetching the ACL of the host when the LUNwith the identifier exists in the storage system.
 13. The computerprogram product of claim 8 wherein applying to the LUN the ACL includessending a dictionary to the storage system.
 14. The computer programproduct of claim 8 wherein the identifier includes a World WideIdentifier (WWID) of the LUN and a iSCSI Qualified Name (IQN) of theLUN.
 15. A computing system including one or more processors and one ormore memories configured to perform operations comprising: creating alogical unit number (LUN) on a storage array node of a storage system;providing an identifier of the LUN of the storage array node to acomputing system, wherein the computing system includes one of a host, aserver, and the storage array node; creating an access control list(ACL) of the computing system; applying to the LUN the ACL of thecomputing system to the LUN based upon, at least in part, theidentifier; discovering and mapping the LUN at the computing system;determining that the computing system has failed; and removing the ACLof the computing system that has failed from the LUN to prevent thecomputing system that has failed from accessing the LUN.
 16. Thecomputing system of claim 15 wherein the identifier includes a WorldWide Identifier (WWID) and a iSCSI Qualified Name (IQN) of the LUN. 17.The computing system of claim 15 wherein the operations further comprisedetermining from the computing system that the LUN with the identifierexists in the storage system.
 18. The computing system of claim 17wherein the operations further comprise fetching the ACL of the hostwhen the LUN with the identifier exists in the storage system.
 19. Thecomputing system of claim 15 wherein applying to the LUN the ACLincludes sending a dictionary to the storage system.
 20. The computingsystem of claim 15 wherein the identifier includes a World WideIdentifier (WWID) of the LUN and a iSCSI Qualified Name (IQN) of theLUN.